Lol I thought it was to accommodate some pretty impressive wingspan (seriously, Ale's flower wings look like they belong on a plane...) - and to prevent a wandering, twirling Rihanna from being smacked in the face :p

I actually like the wide runway. it makes sense since the wings are part of the show and I think it lends versatility to the performers. If you look at the Pink performance with Justin, some of the dancers are up on the cameras and right in front of the front row seats...they may need to make it even wider!